Best way to learn LangChain is to read code that actually ships. These 8 repos are the ones we recommend.
1. langchain-ai/langchain (core)
The framework itself. Read the abstractions — Runnable, Chain, Agent. Top-level API has improved dramatically post-0.3.
2. langchain-ai/langgraph
Stateful agents. Study the examples folder — customer_support_bot.py is the best multi-step agent reference.
3. langchain-ai/open-canvas
Real product built with LangGraph. Editing assistant with artifacts. Production patterns for streaming + persistence.
4. assafelovic/gpt-researcher
AI research agent that produces 5K-word reports with citations. Multi-agent orchestration done right.
5. langfuse/langfuse
Observability for LangChain apps. Self-hostable. Read their integration code for how to instrument production apps.
6. langchain-ai/chat-langchain
The chat-with-LangChain-docs assistant. Open-sourced. Reference for production RAG.
7. jerryjliu/llama_index
Not LangChain, but the alternative — worth comparing patterns. LlamaIndex is more opinionated about indexing.
8. langchain-ai/notebooks
Official notebook tutorials. Run them locally — best onboarding path for new LangChain devs.
What to study (in order)
- Build a basic Runnable chain (prompt → LLM → output parser)
- Add a RAG retriever
- Convert to an Agent with one tool
- Move to LangGraph for stateful flow
- Add observability (LangSmith or Langfuse)
- Productionize: error handling, streaming, persistence
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